At a given depth, the pressure exerted by a liquid is unequal in all directions.

The weight of air in a column of the height of the atmosphere and area $15 \mathrm{cm}\times 15 \mathrm{cm}$ is nearly equal to the weight of an object of mass:
(Take acceleration due to gravity equal to $10 {\mathrm{ms}}^{-2}$ and the atmospheric pressure equal to $101325 \mathrm{Pa}$).